Mounting structure for power storage device

ABSTRACT

A mounting structure for a power storage device includes: a power storage device including a power storage stack and a housing case; a floor member; and a rear bracket. The housing case includes a lower case having a rear wall, and an upper case. The floor member is provided with an attachment portion for attaching the rear bracket. The rear bracket includes a front end portion and a rear end portion that is attached to the attachment portion. The power storage stack is disposed inside the housing case to provide a gap between the power storage stack and the rear wall. The front end portion of the rear bracket is fixed to the rear wall to be located between an upper surface and a lower surface of the power storage stack in an up-down direction.

This nonprovisional application is based on Japanese Patent ApplicationNo. 2020-006576 filed on Jan. 20, 2020 with the Japan Patent Office, theentire contents of which are hereby incorporated by reference.

BACKGROUND Field

The present disclosure relates to a mounting structure for a powerstorage device in a vehicle.

Description of the Background Art

Vehicles such as an electric vehicle and a hybrid vehicle are equippedwith a power storage device for supplying electric power to a motor. Thepower storage device includes a housing case in which a power storagestack is housed. The power storage device is fixed to a floor panel, forexample.

As a conventional mounting structure for a power storage device,Japanese Patent No. 5733089 discloses a technique by which a bracket isused to fix the front side of a housing case to a cross member of avehicle and a reinforce (a reinforcement member) is used to fix the rearside of the housing case to a base mount portion provided on a floorpanel.

In the mounting structure for a power storage device disclosed inJapanese Patent No. 5733089, a power storage device is mounted above thefloor panel. The reinforce is fixed to the lower surface of the housingcase, and inclined downward toward the rear side. Furthermore, insidethe housing case, a power storage stack is fastened with a bolt to abottom portion of the housing case.

SUMMARY

The mounting structure for a power storage device disclosed in JapanesePatent No. 5733089, however, may cause the following situation.Specifically, when a vehicle is collided from behind, an impacttransmitted from the floor panel through the reinforce and received bythe bottom portion of the housing case may be transmitted to the powerstorage stack fixed to the bottom portion. Thus, in order to protect thepower storage stack from damage or the like caused by an impacttransmitted to the power storage stack, countermeasures may need to betaken, for example, by increasing the strengths of parts of thereinforce and the floor panel, a bracket coupling the floor panel andthe housing case, and the housing case itself. Thus, the cost for themounting structure for a power storage device tends to be relativelyhigh.

The present disclosure has been made in consideration of theabove-described problems. An object of the present disclosure is toprovide a mounting structure for a power storage device, which can moreinexpensively suppress transmission of an impact to a power storagestack in a housing case when a vehicle is collided from behind.

A mounting structure for a power storage device according to the presentdisclosure includes: a power storage device including a power storagestack having an upper surface and a lower surface, and a housing case inwhich the power storage stack is housed; a floor member formed as afloor of a vehicle, the power storage device being fixed to the floormember; and a rear bracket for fixing a rear portion of the powerstorage device to the floor member. The housing case includes: a lowercase having a rear wall that faces rearward, a side of the lower surfaceof the power storage stack being fixed to the lower case; and an uppercase fixed to the lower case to cover a side of the upper surface of thepower storage stack. The floor member is provided with an attachmentportion for attaching the rear bracket on a rear side of the rear wall.The rear bracket includes a front end portion fixed to the rear wall,and a rear end portion attached to the attachment portion. The powerstorage stack is disposed inside the housing case to provide a gapbetween the power storage stack and the rear wall. The front end portionof the rear bracket is fixed to the rear wall to be located between theupper surface and the lower surface of the power storage stack in anup-down direction.

According to the above-described configuration, when a vehicle iscollided from behind, an impact received by the floor panel istransmitted through the rear bracket attached to the attachment portionof the floor panel, and then, received by the rear wall of the lowercase. In this case, the front end portion of the rear bracket is fixedto the rear wall of the lower case to be located between the uppersurface and the lower surface of the power storage stack in the up-downdirection. Thus, when an impact is received by the rear wall of thelower case, the rear wall is deformed to pivot around the base portionof the rear wall toward the inside of the housing case. Inside thehousing case, the power storage stack is disposed to provide a gapbetween the power storage stack and the rear wall of the lower case.Thereby, interference of the deformed rear wall with the power storagestack can be suppressed. This can consequently suppress transmission ofan impact to the power storage stack when a vehicle is collided frombehind.

Furthermore, by the above-described configuration, transmission of animpact to the power storage stack can be suppressed without increasingthe rigidity of the lower case itself or the body itself. Thereby, themanufacturing cost can also be reduced.

In the above-described mounting structure for a power storage deviceaccording to the present disclosure, the rear wall has an upper end at aposition lower than the upper surface of the power storage stack in theup-down direction. In this case, the front end portion of the rearbracket is fixed to the rear wall at a position lower than the upper endof the rear wall.

According to the above-described configuration, as compared with thecase where the upper end of the rear wall is located at a positionhigher than the upper surface of the power storage stack, it becomespossible to reduce the distance in which the upper end side of the rearwall moves when the rear wall of the lower case is deformed by a rearcollision to pivot around the base portion of the rear wall toward theinside of the housing case. As a result, interference of the deformedrear wall with the power storage stack can be further suppressed.

In the above-described mounting structure for a power storage deviceaccording to the present disclosure, the power storage stack has a rearsurface that faces rearward. In this case, the rear surface of the powerstorage stack may be provided with a terminal portion that protrudesrearward. Further in this case, the upper end of the rear wall islocated at a position lower than the terminal portion.

According to the above-described configuration, it becomes possible tosuppress interference of the rear wall of the lower case, which isdeformed by a rear collision, with the terminal portion provided on therear surface of the power storage stack. Thereby, transmission of animpact to the terminal portion by a rear collision can be suppressed.

In the above-described mounting structure for a power storage deviceaccording to the present disclosure, the upper case includes a wall thathas a lower end portion located at a position lower than the terminalportion and that faces the rear surface from a rear side. In this case,on a rear side of the terminal portion, the wall has a bulging portionthat bulges more rearward than the lower end portion.

As the rear wall of the lower case is deformed by a rear collision, theupper case fixed to the lower case is also deformed toward the inside ofthe housing case. As in the above-described configuration, on the rearside of the terminal portion, the upper case has a bulging portion thatbulges rearward. Thereby, interference of the deformed upper case withthe terminal portion can be suppressed. Thus, transmission of the impactto the terminal portion by a rear collision can be further suppressed.

In the above-described mounting structure for a power storage deviceaccording to the present disclosure, the front end portion of the rearbracket is welded to the rear wall.

According to the above-described configuration, the rear bracket can befixed stably at a prescribed position as compared with the case wherethe rear bracket is fastened to the rear wall with a fastening member orthe like. Thus, the power storage device can be mounted in a vehiclewith accuracy.

The foregoing and other objects, features, aspects and advantages of thepresent disclosure will become more apparent from the following detaileddescription of the present disclosure when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a part of a vehicle having amounting structure for a power storage device according to anembodiment.

FIG. 2 is a partial cross-sectional view of the vehicle, which is takenalong a line II-II shown in FIG. 1.

FIG. 3 is an enlarged view of a structure at and around a power storagestack in FIG. 2.

FIG. 4 is a diagram showing the state where a rear side of a housingcase is deformed when the vehicle having the mounting structure for apower storage device according to the embodiment is collided frombehind.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, an embodiment of the present disclosure will bedescribed in detail with reference to the accompanying drawings. In theembodiments described below, the same or corresponding components willbe denoted by the same reference characters, and description thereofwill not be repeated.

In the figures, the direction of an arrow U indicates an upwarddirection while the direction of an arrow D indicates a downwarddirection. Also, the direction of an arrow Fr indicates a directionforward of a vehicle while the direction of an arrow Re indicates adirection rearward of the vehicle. Also, the direction of an arrow I,indicates a direction leftward of the vehicle while the direction of anarrow R indicates a direction rightward of the vehicle.

FIG. 1 is a perspective view showing a part of the vehicle having amounting structure for a power storage device according to anembodiment. FIG. 2 is a partial cross-sectional view of the vehicle,which is taken along a line II-II shown in FIG. 1. Referring to FIGS. 1and 2, a vehicle 100 having a mounting structure 10 for a power storagedevice according to an embodiment will be hereinafter described.

As shown in FIGS. 1 and 2, vehicle 100 according to an embodimentincludes mounting structure 10 for a power storage device. Mountingstructure 10 for a power storage device is configured to fix a powerstorage device 30 to vehicle 100. Mounting structure 10 for a powerstorage device is applicable to a hybrid vehicle provided with an engineand a motor generator (each of which is not shown) as a power source.Furthermore, mounting structure 10 for a power storage device is alsoapplicable to an electric vehicle not including an engine (an internalcombustion engine).

As shown in FIG. 1, vehicle 100 to which mounting structure 10 for apower storage device is applied includes a rear cross member 2, afront-side cross member 3, a mar motor 4, a floor member (a floorpanel)20, a power storage device 30, a front bracket 71, and a rearbracket 72.

Mounting structure 10 for a power storage device is mainly formed offloor member 20, power storage device 30, and rear bracket 72, asmentioned above.

Rear cross member 2 and front-side cross member 3 are disposed inparallel in the front-rear direction of vehicle 100. Rear cross member 2and front-side cross member 3 extend in the width direction of thevehicle. Rear cross member 2 and front-side cross member 3 are joined tofloor member (floor panel)20.

Rear cross member 2 is disposed above rear motor 4. Rear cross member 2is disposed at a position higher than front-side cross member 3. Rearcross member 2 is disposed rearward of front-side cross member 3.

Floor member 20 forms a floor of vehicle 100. Floor member 20 includes aflat portion 21 and a curved portion 22. Flat portion 21 is formed to beapproximately flat and extends rearward from front-side cross member 3.Curved portion 22 extends from the rear side of flat portion 21 so as tocurve upward toward rear cross member 2.

Power storage device 30 is disposed above floor member 20 and forward ofcurved portion 22. Power storage device 30 includes a first unit 31 anda second unit 32.

First unit 31 mainly includes a first case portion 50 as a housing case,and a power storage stack 60.

Power storage stack 60 is housed inside first case portion 50. Powerstorage stack 60 has: an upper surface 61 and a lower surface 62 thatface each other in the up-down direction; and a front surface 63 and arear surface 64 that face each other in the front-rear direction. Frontsurface 63 faces forward in the front-rear direction of the vehiclewhile rear surface 64 faces rearward in the front-rear direction of thevehicle. Power storage stack 60 includes a plurality of power storagecells 65.

The plurality of power storage cells 65 are disposed in parallel in thewidth direction of the vehicle. The plurality of power storage cells 65are connected in series, for example. Specifically, each of theplurality of power storage cells 65 has a first terminal portion 66protruding rearward and a second terminal portion 67 protruding forward.First terminal portion 66 is a positive electrode terminal or a negativeelectrode terminal. Second terminal portion 67 is a negative electrodeterminal or a positive electrode terminal so as to be different inpolarity from first terminal portion 66.

A plurality of first terminal portions 66 are disposed on the rearsurface 64 side of power storage stack 60 such that their positiveelectrode terminals and negative electrode terminals are alternatelyarranged in the width direction of the vehicle. A plurality of secondterminal portions 67 are disposed on the front surface 63 side of powerstorage stack 60 such that their positive electrode terminals andnegative electrode terminals are alternately arranged in the widthdirection of the vehicle.

The plurality of first terminal portions 66 are electrically connectedthrough a first bus bar (not shown). Specifically, the positiveelectrode terminal of one power storage cell 65 of two power storagecells 65 adjacent to each other is connected by a bus bar to thenegative electrode terminal of the other power storage cell 65 of thesetwo power storage cells 65.

The plurality of second terminal portions 67 are electrically connectedthrough a second bus bar (not shown). Specifically, the positiveelectrode terminal of one power storage cell 65 of two power storagecells 65 adjacent to each other is connected by a bus bar to thenegative electrode terminal of the other power storage cell 65 of thesetwo power storage cells 65.

Power storage cells 65 adjacent to each other are connected alternatelyby the first bus bar on the rear surface 64 side of power storage stack60 and by the second bus bar on the front surface 63 side of powerstorage stack 60, so that the plurality of power storage cells 65 areconnected in series.

The plurality of first terminal portions 66 correspond to the respectiveterminal portions provided on rear surface 64 of power storage stack 60.

Power storage cell 65 is a secondary battery such as a nickel-metalhydride battery or a lithium-ion battery, for example. Power storagecell 65 has a rectangular shape, for example. It should be noted thatpower storage cell 65 is not limited to a rectangular shape but may be acylindrical shape. Power storage cell 65 may be made of a liquidelectrolyte or may be made of a solid electrolyte. Also, power storagecell 65 is not limited to a secondary battery but may be a capacitorthat can store electric power, and the like.

First case portion 50 includes an upper case 51 and a lower case 52.Lower case 52 has a substantially box shape that opens upward. The lowersurface 62 side of power storage stack 60 is fixed to lower case 52.

Inside lower case 52, a first mounting portion 53 and a second mountingportion 54 are provided, on which power storage stack 60 is to bemounted. First mounting portion 53 and second mounting portion 54 aredisposed inside lower case 52 to provide a gap between first mountingportion 53 and second mounting portion 54 in the front-rear direction ofthe vehicle. Lower surface 62 of power storage stack 60 has both ends inthe front-rear direction of the vehicle. Each of both ends is fixed to acorresponding one of first mounting portion 53 and second mountingportion 54. Power storage stack 60 is disposed to provide a gap betweenpower storage stack 60 and a rear wall 52 b (see FIG. 3) of lower case52.

Upper case 51 has a substantially box shape that opens downward.Uppercase 51 is provided to cover the upper surface 61 side of powerstorage stack 60. Upper case 51 is fixed to lower case 52.

Second unit 32 mainly includes a second case portion 40, a junction box43, and a monitoring unit 44. Junction box 43 and monitoring unit 44 arehoused in second case portion 40.

Each of junction box 43 and monitoring unit 44 is electrically connectedto power storage stack 60. Junction box 43 serves as a connector ofwires connecting to power storage stack 60 and to a motor generator andthe like through a converter (not shown) and an inverter (not shown).Monitoring unit 44 monitors the state of each of power storage cells 65in power storage stack 60.

Front bracket 71 serves to fix the front side of power storage device 30to floor member 20. Front bracket 71 is disposed to extend in thefront-rear direction of the vehicle. The front end side of front bracket71 is fastened to front-side cross member 3. On the rear side offront-side cross member 3 and on the front side of lower case 52, frontbracket 71 is fastened to an attachment portion 81 provided on floormember 20.

Front bracket 71 is fixed on the front side of lower case 52.Specifically, it is preferable that the rear end side of front bracket71 is welded onto the front end side of lower case 52. Thereby, frontbracket 71 can be stably fixed at a prescribed position. Accordingly,variations in position of attachment to floor member 20 can besuppressed, and thus, front bracket 71 can be reduced in size.

Rear bracket 72 serves to fix the rear portion of power storage device30 to floor member 20. Rear bracket 72 is disposed on the rear side oflower case 52 to extend rearward.

Rear bracket 72 includes a front end portion 721 and a rear end portion722. Front end portion 721 is disposed to extend in the up-downdirection. Rear end portion 722 is disposed to extend rearward from theupper end portion of front end portion 721. On the rear side of lowercase 52, rear end portion 722 is attached to an attachment portion 82provided on floor member 20.

Rear bracket 72 is fixed to rear wall 52 b (see FIG. 3) of lower case52. Rear wall 52 b is provided to face rearward of vehicle 100.Specifically, front end portion 721 of rear bracket 72 is fixed to rearwall 52 b to be located between upper surface 61 and lower surface 62 ofpower storage stack 60 in the up-down direction.

Also, it is preferable that front end portion 721 of rear bracket 72 iswelded onto rear wall 52 b. Thereby, rear bracket 72 can be stably fixedat a prescribed position. Accordingly, variations in position ofattachment to floor member 20 can be suppressed, and thus, rear bracket72 can be reduced in size.

FIG. 3 is an enlarged view of a structure at and around the powerstorage stack in FIG. 2. Referring to the above-mentioned FIG. 2 andFIG. 3, the structure at and around power storage stack 60 will then bedescribed.

Upper case 51 provided so as to cover the upper side of power storagestack 60 has a wall 51 b that faces, from the rear side, the upperportion of rear surface 64 of power storage stack 60. Wall 51 b has alower end portion 51 b 2 at a position lower than the terminal portion(the above-mentioned first terminal portion 66) provided on rear surface64 of power storage stack 60. Lower end portion 51 b 2 is fixed to rearwall 52 b of lower case 52, for example.

On the rear side of the above-mentioned terminal portion (theabove-mentioned first terminal portion 66), wall 15 b has a bulgingportion 51 b 1 that bulges more rearward than lower end portion 51 b 2.In other words, in the front-rear direction of the vehicle, the distancefrom rear surface 64 of power storage stack 60 to bulging portion 51 b 1is longer than the distance from rear surface 64 to lower end portion 51b 2.

Furthermore, rear wall 52 b of lower case 52 has an upper end 52 b 1located at a position lower than upper surface 61 of power storage stack60 in the up-down direction. Upper end 52 b 1 is located at a positionlower than the terminal portion (the above-mentioned first terminalportion 66) provided on rear surface 64 of power storage stack 60.

Front end portion 721 of rear bracket 72 is fixed to rear wall 52 b at aposition lower than upper end 52 b 1 of rear wall 52 b.

FIG. 4 is a diagram showing the state where the rear side of the housingcase is deformed when the vehicle having the mounting structure for apower storage device according to the embodiment is collided frombehind. Referring to FIG. 4, an explanation will be hereinafter givenwith regard to the state where the rear side of the housing case isdeformed when vehicle 100 is collided from behind.

As shown in FIG. 4, when vehicle 100 is collided from behind, rear motor4 moves forward to push curved portion 22 of floor member 20. Thereby,an impact as indicated by an arrow AR1 is received by rear bracket 72and transmitted through this rear bracket 72 to rear wall 52 b.

In this case, front end portion 721 of rear bracket 72 is fixed to rearwall 52 b of lower case 52 so as to be located between upper surface 61and lower surface 62 of the power storage stack in the up-downdirection. Thus, when rear wall 52 b of lower case 52 receives animpact, rear wall 52 b is deformed to pivot around the base portion ofrear wall 52 b toward the inside of first case portion (housing case)50, as indicated by a dashed line in FIG. 4. Inside first case portion50, power storage stack 60 is disposed to provide a gap between powerstorage stack 60 and rear wall 52 b of lower case 52. Thus, interferenceof the deformed rear wall 52 b with power storage stack 60 can besuppressed. As a result, when vehicle 100 is collided from behind,transmission of an impact to power storage stack 60 can be suppressed.

Furthermore, transmission of an impact to power storage stack 60 can besuppressed without increasing the rigidity of the lower case itself orthe body itself. Thereby, the manufacturing cost can also be reduced.

Furthermore, upper end 52 b 1 of rear wall 52 b is located at a positionlower than upper surface 61 of power storage stack 60, and front endportion 721 of rear bracket 72 is fixed to rear wall 52 b at a positionlower than upper end 52 b 1 of rear wall 52 b.

Thus, when rear wall 52 b is deformed as described above due to a rearcollision, the moving distance of upper end 52 b 1 of rear wall 52 b canbe reduced as compared with the case where upper end 52 b 1 of rear wall52 b is located at a position higher than upper surface 61 of powerstorage stack 60. As a result, interference of the deformed rear wall 52b with power storage stack 60 can be further suppressed.

In addition, upper end 52 b 1 of rear wall 52 b is located at a positionlower than the terminal portion (the above-mentioned first terminalportion 66) provided on rear surface 64 of power storage stack 60. Thus,it becomes possible to suppress interference of rear wall 52 b of thelower case, which is deformed by a rear collision, with the terminalportion (first terminal portion 66) provided on rear surface 64 of powerstorage stack 60. Thereby, transmission of an impact to the terminalportion (first terminal portion 66) by a rear collision can besuppressed.

Furthermore, on the rear side of the above-mentioned terminal portion(first terminal portion 66), wall 51 b of upper case 51 is provided withbulging portion 5 b 1 that bulges more rearward than lower end portion51 b 2 of wall 51 b.

When rear wall 52 b of lower case 52 is deformed as described above dueto a rear collision, upper case SI (specifically, wall 51 b of uppercase 51) fixed to lower case 52 is also deformed toward the inside offirst case portion 50, as indicated by the dashed line in FIG. 4. Alsoin such a case, bulging portions 51 b 1 provided as described above cansuppress interference of the deformed upper case 51 with theabove-mentioned terminal portion.

Although the present disclosure has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the scopeof the present disclosure being interpreted by the terms of the appendedclaims.

What is claimed is:
 1. A mounting structure for a power storage device,the mounting structure comprising: a power storage device including apower storage stack having an upper surface and a lower surface, and ahousing case in which the power storage stack is housed; a floor memberformed as a floor of a vehicle, the power storage device being fixed tothe floor member; and a rear bracket for fixing a rear portion of thepower storage device to the floor member, wherein the housing caseincludes a lower case having a rear wall that faces rearward, a side ofthe lower surface of the power storage stack being fixed to the lowercase, and an upper case fixed to the lower case to cover a side of theupper surface of the power storage stack, the floor member is providedwith an attachment portion for attaching the rear bracket on a rear sideof the rear wall, the rear bracket includes a front end portion fixed tothe rear wall, and a rear end portion attached to the attachmentportion, the power storage stack is disposed inside the housing case toprovide a gap between the power storage stack and the rear wall, and thefront end portion of the rear bracket is fixed to the rear wall to belocated between the upper surface and the lower surface of the powerstorage stack in an up-down direction.
 2. The mounting structure for apower storage device according to claim 1, wherein the rear wall has anupper end at a position lower than the upper surface of the powerstorage stack in the up-down direction, and the front end portion of therear bracket is fixed to the rear wall at a position lower than theupper end of the rear wall.
 3. The mounting structure for a powerstorage device according to claim 2, wherein the power storage stack hasa rear surface that faces rearward, the rear surface of the powerstorage stack is provided with a terminal portion that protrudesrearward, and the upper end of the rear wall is located at a positionlower than the terminal portion.
 4. The mounting structure for a powerstorage device according to claim 3, wherein the upper case includes awall that has a lower end portion located at a position lower than theterminal portion, and that faces the rear surface from a rear side, andon a rear side of the terminal portion, the wall has a bulging portionthat bulges more rearward than the lower end portion.
 5. The mountingstructure for a power storage device according to claim 1, wherein thefront end portion of the rear bracket is welded to the rear wall.